Evaluation of Post-Processing on Additive Manufactured\nBioresorbable Polymers for Medical Devices

Additive manufacturing (AM) has seen\nmassive growth in the medical\ndevice sector and an increase in the clearance of devices. Many challenges\nstill exist in the design, development, and clinical use of AM-fabricated\ndevices, notably the processing, annealing, and sterilization of resorbable\npolymers. In addition, the use of these materials continues to grow\nin medical devices and scaffold technologies for tissue engineering\nand regenerative medicine (TERM). Specifically, this study focused\non the scaffold mechanical properties post-processing and throughout\na simulated resorption (in vitro) study. Herein, we evaluated three\n(3) materials that span a range of mechanical properties and degradation\nrates relating to a range of tissue healing rates and mechanical properties\naffording the opportunity of biomimetic potentials, Caproprene 100M,\nLactoflex 7415, and Lactoprene 100M. These bioresorbable polymers\nwere additively manufactured into scaffold forms of Type V tensile\nbars to investigate post-processing parameters. A range of heat treatments\nwere then performed after the AM process to induce a range of semicrystalline\nmorphologies, and subsequently, two different sterilization techniques\nwere performed, one based on super critical carbon dioxide and another\nusing electron beam radiation. It was statistically shown that the\nheat treatment parameters and the sterilization method had statistically\nsignificant effects on the scaffold properties of each material. While\nmaterial differences were responsible for the majority of the mechanical\nproperty breadth, techniques utilizing analysis of variance allowed\nthe observation of significant effects and interactions associated\nwith heat treatment, sterilization, and material parameters (alpha\n= 0.05). The characterization of the sample groups provided insight\ninto the process–structure–property–performance\nrelationships of the resorbable scaffold samples. It was established\nthat the post-processing impacted the scaffold structures, and therefore,\nsterilization and heat treatment selections should be included within\ninitial design considerations alongside material selection as critical\nfor device development, especially when AM bioresorbable scaffolds\nfor TERM.